Semi-permeable expanding sleeve system for borehole pipe spreading configurations and method of spreading pipes in a borehole

ABSTRACT

A semi-permeable expanding sleeve system for pipe spreading in a borehole is disclosed. The system has an expansion sleeve, a grout injection pipe and a high-solids grout mixture. The expansion sleeve has a top end and a bottom end. The grout injection pipe has a first end, a second end, an inlet and at least one outlet. The grout injection pipe is insertable through the open top end of the expansion sleeve such that the at least one outlet is positionable within the expansion sleeve and the inlet is positionable adjacent the top end of the expansion sleeve. The grout mixture is pumped through the grout injection pipe into the expansion sleeve using a pump. A closing mechanism is provided for closing the expansion sleeve around the grout injection pipe to create a semi-permeable enclosure.

FIELD OF THE DISCLOSURE

The present application relates generally to a spacer for a verticalground heat exchanger utilizing vertical closed-loops within eachborehole. More specifically, this application relates to a spacer foruse in geo-exchange systems that can operate using this type of groundheat exchanger.

BACKGROUND

This section provides background information to facilitate a betterunderstanding of the various aspects of the invention. It should beunderstood that the statements in this section of this document are tobe read in this light, and not as admissions of prior art.

A vertical ground heat exchanger comprises at least onevertically-drilled hole (borehole) in a geological formation. Dependingupon the application and contractor preferences, boreholes can vary indiameter and depth to a significant degree.

The borehole contains one or more vertical closed loops (VCLs), eachcomprising two pipes joined at the bottom of the hole with a u-shapedbend or fitting. The vertical closed loops (VCLs) are connected at thetop of the hole to the supply and return sections of a fluid transfersystem. The vertical closed loops (VCLs) and fluid transfer system areused to transport a heat transfer fluid that will carry heat to or fromthe geological formation.

Installation of vertical closed loops (VCLs) is followed by filling ofthe voids in the drilled borehole with a grouting material to provide asuitable medium for transfer of heat between the VCLs and the ground andto seal the borehole. Properly sealing the borehole by grouting the voidspace between the vertical closed loops piping and the borehole willprotect aquifers from contamination and loss of natural artesianpressure. Grouting material is conveyed to the entire depth of thedrilled borehole through use of a tremie line that is typically pulledup during the grouting process to reduce pumping pressure.

An important factor in the efficiency of a vertical ground heatexchanger is the proximity between the vertical closed loop pipes usedto transfer heat to and from the geological formation and the wall ofthe borehole in the formation. Basic and conventional systems, shown inFIG. 1, make no particular effort to improve this proximity.

Referring to FIG. 2, a known method of improving proximity between thepipes and the geological formation is to use mechanical clip spacers.U-tubes with mechanical clip spacers in vertical ground heat exchangersimprove the proximity and the benefits of improving this proximity arewell documented: adding 20-35% higher efficiency by reducing thermalresistance in the borehole. The current practice of using plastic/metalclips at spaced intervals in the ground lacks uniformity in the amountof spreading.

BRIEF SUMMARY

There is provided a semi-permeable expanding sleeve system for pipespreading in a borehole has an expansion sleeve, a grout injection pipe,a grout mixture and a pump suitable for handling the grout. Theexpansion sleeve has a top end and a bottom end. The grout injectionpipe has a top end, a bottom end, an inlet and at least one outlet. Thegrout injection pipe is insertable through the top end of the expansionsleeve such that the at least one outlet is positioned within theexpansion sleeve and the inlet is positioned adjacent the top end of theexpansion sleeve. The grout mixture is pumped through the groutinjection pipe and into the expansion sleeve using a pump. A closingmechanism is provided for closing the expansion sleeve around the groutinjection pipe.

In one embodiment, the expansion sleeve is made of a loose weave fabricthat has gaps between fibers of 0.03-0.08 inches. This size of gapallows smaller-sized solids to pass through it easily while reducing orpreventing passage of larger solids, leading to the characterization ofthe sleeve as “semi-permeable”. Natural, untreated burlap fabric is oneexample of an acceptable fabric that can be used. Any fabric materialwill deteriorate in the wet, earthy conditions of the grouted boreholebut natural, untreated burlap will do so quickly, without leaving behindchemical residues.

In one embodiment, the expansion sleeve is the same length as the pipesto be spread. This may allow for a more uniform spreading of the pipeswhen the expansion sleeve is filled with grout. The expansion sleeve mayalso have a diameter equal to the diameter of the borehole minus twotimes the outer diameter of the smallest pipe within the borehole.

In one embodiment, the grout injection pipe is made of plastic.

In one embodiment, the grout injection pipe has a plurality of outletsalong a length of the grout injection pipe.

In one embodiment, the grout mixture is a high-solids mixture, meaningthat at least 50% of the volume of the mixture is made up of solidmaterial comprising bentonite (clay) grout and sand.

In one embodiment, the pump is a positive-displacement pump.

There is also provided a method of spreading pipes in a borehole. Anexpansion sleeve and grout injection pipe are provided. The expansionsleeve has a top end and a bottom end and the grout injection pipe has atop end, a bottom end, an inlet and at least one outlet. The groutinjection pipe is inserted into the expansion sleeve through the firstend of the expansion sleeve such that the at least one outlet of thegrout injection pipe is adjacent the bottom end of the expansion sleeve.The inlet of the grout injection pipe protrudes from the top end of theexpansion sleeve. The bottom end of the expansion sleeve is closed tocreate a semi-permeable enclosure. The semi-permeable enclosure isinserted into a borehole that has pipes to be spread. The semi-permeableenclosure is positioned in a central location of the borehole relativeto the pipes to be spread. A grout mixture is pumped through the inletof the grout injection pipe such that it travels through the at leastone outlet of the grout injection pipe into the expansion sleeve. Thiscauses the expansion sleeve to fill with grout and forces the pipesoutward towards a wall of the borehole as the expansion sleeve expands.

In one embodiment, a further step of closing the top end of theexpansion sleeve around the grout injection pipe is completed.

In one embodiment, the expansion sleeve is closed around the groutinjection pipe with a clamp.

In one embodiment, the expansion sleeve is made of a loose weave fabricthat has gaps between fibers of 0.03-0.08 inches. Burlap fabric is oneexample of an acceptable fabric that can be used.

In one embodiment, the expansion sleeve is the same length as the pipesto be spread. This may allow for a more uniform spreading of the pipeswhen the expansion sleeve is filled with grout. The expansion sleeve mayalso have a diameter equal to the diameter of the borehole minus twotimes the outer diameter of the smallest pipe within the borehole.

In one embodiment, the grout injection pipe is made of plastic.

In one embodiment, a grout pipe cap is used to seal the bottom end ofthe grout injection pipe.

In one embodiment, the grout injection pipe has a plurality of outletsalong a length of the grout injection pipe.

In one embodiment, the grout mixture is high-solids mixture, meaningthat at least 50% of the volume of the mixture is made up of solidmaterial comprising bentonite (clay) grout and sand.

In one embodiment, the pump is a positive displacement pump.

In one embodiment, there is a further step of trimming the open top endof the expansion sleeve to allow the inlet of the grout injection pipeto protrude from the expansion sleeve.

In one embodiment, there is a further step of connecting the inlet ofthe grout injection pipe to a water supply system for maintaining watercontent within the grout mixture and geological form in which theborehole is made.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the followingdescription in which references are made to the following drawings, inwhich numerical references denote like parts. The drawings are for thepurpose of illustration only and are not intended to in any way limitthe scope of the invention to the particular embodiments shown.

FIG. 1 is a side elevation view of a conventional borehole with U-tubepipes inserted.

FIG. 2 is a side elevation view of a borehole with U-tube pipes insertedand spaced with spacers.

FIG. 3 is a side elevation view of a semi-permeable expanding sleeveinstalled within a borehole.

FIG. 4 is a top plan view of the semi-permeable expanding sleeveinstalled within a borehole prior to pumping in grout.

FIG. 5 is a top plan view of the semi-permeable expanding sleeveinstalled within the borehole after grouting is completed.

FIG. 6 is a side elevation view, partially in section, of an embodimentof the semi-permeable expanding sleeve system installed within aborehole.

FIG. 7 is a detailed view of the top end of the semi-permeable expandingsleeve shown in FIG. 6.

FIG. 8 is a detailed view of the bottom end of the semi-permeableexpanding sleeve shown in FIG. 6.

FIG. 9 is a side elevation view, partially in section, of thesemi-permeable expanding sleeve system installed within a borehole withan open top end.

FIG. 10 is a detailed view of the top end of the semi-permeableexpanding sleeve shown in FIG. 9.

FIG. 11 is a detailed view of the top end of the semi-permeableexpanding sleeve shown in FIG. 9.

FIG. 12 is a side elevation view, partially in section, an alternativeembodiment of the system using a removable tremie line.

FIG. 13 is a detailed view of the top end of the system shown in FIG. 12

FIG. 14 is a detailed view of the bottom end of the system shown in FIG.12.

FIG. 15 is a side elevation view, partially in section, of analternative embodiment of the system using an expanding sleeve with thebottom sewn shut and a removable tremie line.

FIG. 16 is a detailed view of the top end of the system shown in FIG.15.

FIG. 17 is a detailed view of the bottom end of the system shown in FIG.15.

FIG. 18 is a side elevation view of the vertical closed loops as theywould be positioned downhole.

FIG. 19 is a detailed view of the bottom end of the tremie line shown inFIG. 18

FIG. 20 is a schematic view of the system during the grouting process.

FIG. 21 is a schematic view of a water supply system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A semi-permeable expanding sleeve system, generally identified byreference numeral 10, will now be described with reference to FIG. 3through FIG. 21.

Referring to FIG. 3, semi-permeable expanding sleeve system 10 has anexpansion sleeve 12, a grout injection pipe 14, a grout mixture 18 and apump 20. Expansion sleeve 12 has a top end 22 and a bottom end 24. Groutinjection pipe 14 has a top end 26, a bottom end 28, an inlet 30 and anoutlet 32. Grout injection pipe 14 is inserted through open top end 22of expansion sleeve 12 such that outlet 32 is positioned withinexpansion sleeve 12 and inlet 30 is positioned adjacent top end 22 ofexpansion sleeve 12. Grout mixture 18 is made up of water, silica sandand powdered bentonite clay. Pump 20 pumps grout mixture 18 throughgrout injection pipe 14 and into expansion sleeve 12. Apositive-displacement pump is effective in system 10. System 10 isgenerally used to spread pipes 34 of vertical closed-loops (VCLs) 36placed within a borehole 38. As can be seen in FIG. 4, prior toexpansion of expansion sleeve 12, pipes 34 are unevenly spaced andpositioned at a distance from borehole walls 40. Referring to FIG. 5,after expansion of expansion sleeve 12, pipes are pushed adjacentborehole walls 40.

Referring to FIG. 3, in the embodiment shown, expansion sleeve 12 ismade of a coarse fabric with a loose weave containing gaps of 0.03-0.08inches (0.762-2.032 mm) between fibers. An example of an appropriatematerial is natural, untreated burlap with a fabric weight ofapproximately 10 ounces per square yard (339 g/m²). In one embodiment,expansion sleeve 12 is substantially the same length as pipes 34 to bespread and the diameter of the expansion sleeve 12 is substantially thesame as the diameter of the borehole.

When making expansion sleeve 12, fabric needs to be cut to a length justslightly longer than the pipes to be spread. This allows for easymanipulation of expansion sleeve 12 when preparing for grouting. The cutwidth should be within an approximate range as follows. Referring toFIG. 8, the maximum cut width would be approximately the circumferenceof the circle defined by the borehole wall 40. Specifically, Max CutWidth=π* (borehole diameter)+seam allowance. The minimum cut width wouldbe at least the circumference of a circle defined by the borehole wall40 and the pipes 34 of the VCL. Specifically, Min Cut Width=π* (boreholediameter−2* pipe diameter)+seam allowance. A cut width outside of thisrange can impair the function of the expansion sleeve. Once the sleevefabric is cut to the desired length and width, the sleeve fabric is sewninto a sleeve. The fabric is folded along its long edge and the fabricis sewn together along its length. The bottom end of the fabric may besewn together to create a closed bottom end 24 of expansion sleeve 12 orbottom end 24 may remain open. Once sewn, expansion sleeve 12 is turnedinside out so that the seam allowance is on the inside of expansionsleeve 12.

Grout injection pipe 14 is similar to what is known as a tremie line 42in the geo-exchange industry. However, grout injection pipe 14 differsin configuration and use when compared to configuration and use oftremie lines 42. In one embodiment, grout injection pipe 14 isconstructed from a 1 inch diameter high-density polyethylene (HDPE)pipe. Preferably, grout injection pipe 14 is cut to a length longer thanexpansion sleeve 12, 2-3 feet longer than expansion sleeve 12 would bean acceptable length. Referring to FIG. 3, in the embodiment shown,grout injection pipe 14 has top end 26 and bottom end 28. Top end 26doubles as inlet 30 while bottom end 28 is capped with a grout pipe cap16. A plurality of outlets 32 with a diameter of 0.5 inches (1.25 cm)are drilled through the side 37 of grout injection pipe 14 at variousdistances along the length of grout injection pipe 14. In oneembodiment, outlets 32 are drilled every 1.5 feet for 9 feet, then every3 feet for an additional 30 feet and then every 6 feet for an additional60 feet. These measurements start from capped bottom end 28 of groutinjection pipe 14. This configuration reduces the resistance at lowerelevations in borehole 38 and encourages preferential flow at the lowestconvenient elevation while allowing for easier filling of borehole 38and reducing pumping pressure. A person of skill will understand thattop end 26 of grout injection pipe 14 may double as inlet 30 and bottomend 28 of grout injection pipe 14 may double as outlet 32, when outlet32 is not capped. It will also be understood that grout injection pipe14 can be different lengths and that the positioning of multiple outlets32 along the length of grout injection pipe 14 may be different fromwhat is described above.

Grout mixture 14 is a high-solids grout mixture. Grout is used in thegeo-exchange industry to fill and seal voids in boreholes 38. Thehigh-solids grout mixture is a combination of water, dry silica sand andpowdered bentonite clay grout. The silica sand is preferably 30-70 mesh.When grout mixture 14 is mixed, the bentonite clay absorbs the water andexpands to create a suspension of the solid sand within a viscous,gelatinous fluid. A variety of different ratios may be used to createthe high-solids grout mixture 14, as long as the mixture contains atleast 50% solids by volume and at least 25% sand by volume. The functionof expansion sleeve 12 is partially dependent on the composition of thegrout mixture 18 used to fill expansion sleeve 12. The solids in themixture are comprised of a mix of clay and sand. When pumped intoexpansion sleeve 12, the clay solids will tend to pass through expansionsleeve 12 while the sand solids will remain inside expansion sleeve 12.A mixture containing at least 50% solids by volume and at least 25% sandby volume allows for the proportion of material that passes throughexpansion sleeve 12 to be balanced against the material that remainsinside expansion sleeve 12. This balance helps to ensure that expansionsleeve 12 expands and is filled at the similar rate to void betweenexpansion sleeve 12 and borehole wall 40. It can help to preventborehole 38 from filling with grout 18 before expansion sleeve 12 hasfilled and expanded, allowing expansion sleeve 12 to work as intended.IT may also prevent expansion sleeve 12 from becoming full beforeborehole 38 is fully grouted, creating voids in borehole 38 that areunfilled and unsealed or requiring additional pumping into expansionsleeve 12 that may cause a rupture in expansion sleeve 12.

Once expansion sleeve 12 is sewn and grout injection pipe 14 is cut anddrilled, grout injection pipe 14 is inserted into expansion sleeve 12.Referring to FIGS. 6 - 8, in the embodiment shown, bottom end 28 ofgrout injection pipe 14 protrudes from bottom end 24 of expansion sleeve12 by approximately 2 inches. Bottom end 28 is capped by grout pipe cap16. A flange 44 around the open end of grout pipe cap 16 is positionedinside expansion sleeve 12. As shown in FIG. 8, flange 44 prevents aclosure mechanism 46 from sliding off bottom end 28 of grout injectionpipe 14. Top end 26 of grout injection pipe 14 protrudes from top end 22of expansion sleeve 12 by a small amount, defined only as that requiredto ease manipulation of expansion sleeve 12 and grout injection pipe 14for grouting. In this embodiment, top end 26 of grout injection pipe 14doubles as inlet 30 of grout injection pipe 14.

Expansion sleeve 12 is closed around grout injection pipe 14 using groutpipe cap 16. Expansion sleeve 12 is closed around grout pipe cap 16below flange 43 of grout pipe cap 16 such that flange 44 preventsclosure mechanism 46 from sliding off grout pipe cap 16. This results inoutlets 32 being positioned within expansion sleeve 12 and inlet 30being positioned adjacent and exterior to expansion sleeve 12. Closuremechanism 46 can take the form of clamps, twine, rope, tape, or otherappropriate devices known in the art to minimize leakage between groutinjection pipe 14 and expansion sleeve 12. Closure at bottom end 24 ofexpansion sleeve 12 should be located between bottom end 28 of groutinjection pipe 14 and outlet 32 positioned closest to bottom end 28 ofgrout injection pipe 14. Expansion sleeve 12 is also closed around groutinjection pipe 14 near top end 26. Expansion sleeve 12 closure can belocated at any convenient location near top end 26 of grout injectionpipe 14. All outlets 32 of grout injection pipe 14 should be containedwithin expansion sleeve 12.

In an alternative embodiment shown in FIGS. 9-11, top end 22 ofexpansion sleeve 12 is not closed around grout injection pipe 14 and issimply held to prevent top end 22 from sliding into borehole 38 duringgrouting. The properties of the semi-permeable fabric and high-solidsgrout allow system 10 to function properly even when top end 22 ofexpansion sleeve 12 is open.

In an alternative embodiment shown in FIGS. 12-14, grout injection pipe14 is replaced by standard tremie line 42, and tremie line 42 isconnected to grout pipe cap 16 with a breakable connector 45. Bottom end24 of expansion sleeve 12 is closed around grout pipe cap 16 below theflange of grout pipe cap 16 such that flange 44 prevents closuremechanism 46 from sliding off grout pipe cap 16. Top end 22 of expansionsleeve 12 is not closed around tremie line 42. Before the groutingprocess begins, tremie line 42 is twisted and pulled so that it breaksbreakable connector 45 and is free from grout pipe cap 16, and tremieline 42 can be withdrawn during the grouting process.

In an alternative embodiment shown in FIGS. 15-17, bottom end 24 ofexpansion sleeve 12 is sewn closed. In this embodiment, there is no wayto connect grout injection pipe 14 to the other components at the bottomof the assembly without puncturing expansion sleeve 12. A tremie line 42generally replaces injection pipe 14 in this scenario. Bottom end 28 oftremie line 42 is inserted into expansion sleeve 12 through top end 22of expansion sleeve 12.

Once expansion sleeve 12 and grout injection pipe 14 are combined tocreate a semi-permeable enclosure, semi-permeable expanding sleevesystem 10 is combined with vertical closed-loops (VCLs) 36 to beinserted into borehole 38. Referring to FIGS. 18 and 19, when multiplevertical closed-loops (VCLs) 36 are inserted in the same borehole 38,they are nested within each other at offset angles to ensure a close fitbetween fittings. U-bend fittings 48 at the end of each verticalclosed-loops (VCLs) 36 are then linked together. The bottom end ofsemi-permeable expanding sleeve system 10 is positioned such that bottomend 26 of grout injection pipe 14 is located between pipes 34 ofinnermost vertical closed-loops (VCLs) 36. When grout pipe cap 16 isused, group pipe cap 16 is positioned between pipes 34 of innermostvertical closed-loops (VCLs). Grout pipe cap 16 is then linked to U-bendfitting 48 of innermost vertical closed-loops (VCLs) 36. The placementof the bottom end of semi-permeable expanding sleeve system 10 is theonly absolute placement possible. Although ideally semi-permeableexpanding sleeve system 10 is located exactly between verticalclosed-loops (VCLs) 36 for the entire length of piping 34, the flexiblenature of the installed system 10 prevents absolute placement. This doesnot impact the effectiveness of semi-permeable expanding sleeve system10, as expansion sleeve 12 will push pipes 34 outwards along the entirelength of pipes 34 even if there is not ideal placement. In thepreferred embodiment, pipes 34 are pushed against borehole walls 40 ofboreholes 38 when expansion sleeve 12 is expanded.

After installation into borehole 38, top end 22 of expansion sleeve 12should be trimmed, if needed, so that when grout injection pipe 14 istrimmed short after borehole 38 is filled with high-solids grout mixture18, top end 22 of expansion sleeve 12 can remain closed and undisturbed.If top end 22 of expansion sleeve 12 is below, at, or within 3 inches ofthe ground level 50 beside borehole 38, no trimming is required. If topend 22 of expansion sleeve 12 is higher than 3 inches above ground level50, top end 22 of expansion sleeve 12 should be trimmed until it ispositioned no more than 3 inches above ground level 50. Thisrecommendation applies to all system embodiments, including when top end22 of expansion sleeve 12 is closed and when it is open. As shown inFIG. 20, top end 26 of grout injection pipe 14 is connected to pump 20which is in turn connected to a holding tank 52 which holds high-solidsgrout mixture 18. A positive-displacement pump is ideal for therequirements of system 10, however a person of skill will understandthat other types of pumps 20 in other configurations may also work.High-solids Grout mixture 18 is pumped through inlet 30 of groutinjection pipe 14 and flows out through outlets 32 into expansion sleeve12.

When high-solids grout mixture 18 is pumped into expansion sleeve 12through grout injection pipe 14, the fabric of expansion sleeve 12provides resistance to the flow of grout mixture 18. This resistance isdriven primarily by the solids (silica sand) within grout mixture 18.The solid particles cling to the fibers of the fabric, partiallyblocking gaps and reducing the ability of the fluid component (water andbentonite clay mixture) of grout mixture 18 to pass through gaps. Theresistance to flow creates an accumulation of high-solids grout mixture18 within expansion sleeve 12 creating an increasing pressure withinexpansion sleeve 12 and causing expansion sleeve 12 to expand outwards.Expansion sleeve 12 has the capabilities of occupying a significantspace in borehole 38 when expanded and exerts sufficient force on pipes34 of vertical closed-loops (VCLs) 36 to move them outwards and intocontact with borehole wall 40. The semi-permeable fabric of expansionsleeve 12 allows some of high-solids grout mixture 18 to pass throughand fill the space between expansion sleeve 12 and borehole wall 40 nototherwise occupied by vertical closed-loops (VCLs) 36. High-solids groutmixture 18 is pumped through grout injection pipe 14 until entireborehole 38 is filled with high-solids grout mixture 14. Once expansionsleeve 12 is completely full, the pressure forces high-solids groutmixture 18 through gaps of expansion sleeve 12 until the voids inborehole 38 outside of expansion sleeve 12 are completely filled. Whenborehole 38 is visibly filled with high-solids grout mixture 14, thegrouting process is considered complete.

Once the grouting process is complete, the connection between pump 20and grout injection pipe 14 is severed. Grout injection pipe 14 is thencut to length just above top end 22 of expansion sleeve 12 and isplugged. Expansion sleeve 12, grout injection pipe 14 and grout mixture18 remain in place within borehole 38.

In one embodiment of system 10, shown in FIG. 21, at the completion ofthe grouting process, grout injection pipe 14 is not cut short andplugged. Instead, grout injection pipe 14 is repurposed as part of awater supply system 54. This water supply system 54 is intended to beused during the operation of high temperature geo-exchange systems tomaintain the soil hydration. Under lower temperature conditions (<25°C.) there is little concern of the water content of the geologicalformation or high-solids grout mixture 18. Under higher temperatureconditions (>25° C.), however, there is a concern that the watercontained within geological formation and high-solids grout mixture 18will be driven out of system 10 by the high temperatures. This couldoccur through migration of the water via convective flow or throughevaporation of the water. Given the heat capacity and heat transferproperties of water, the loss of water in the geological formation andhigh-solids grout mixture 18 can significantly impact the storagecapacity and heat transfer efficiency of system 10. Preparation for thissystem requires purging high-solids grout mixture 18 from groutinjection pipe 14. Following the clearing of high-solids grout mixture18, grout injection pipe 14 is filled with a column of water, removingthe air column. Grout injection pipe 14 is then connected towater-supply header 56 and linked together with other grout injectionpipes 14 in bore field. Water-supply header 56 is connected to a waterpump 58 that is specified and sized to provide a small amount ofpressure to the water in water supply system 54. This water pressure issufficient to ensure that any water migrating from grout injection pipe14 into high-solids grout mixture 18 in borehole 38 is replaced. It ispreferred that water pump 56 is supplied from water tank 60, which iskept full by a source of treated or potable water source so as not tocontaminate ground water.

Any use herein of any terms describing an interaction between elementsis not meant to limit the interaction to direct interaction between thesubject elements, and may also include indirect interaction between theelements such as through secondary or intermediary structure unlessspecifically stated otherwise.

In this patent document, the word “comprising” is used in itsnon-limiting sense to mean that items following the word are included,but items not specifically mentioned are not excluded. A reference to anelement by the indefinite article “a” does not exclude the possibilitythat more than one of the element is present, unless the context clearlyrequires that there be one and only one of the elements.

It will be apparent that changes may be made to the illustrativeembodiments, while falling within the scope of the invention. As such,the scope of the following claims should not be limited by the preferredembodiments set forth in the examples and drawings described above, butshould be given the broadest interpretation consistent with thedescription as a whole.

What is claimed is:
 1. A semi-permeable expanding sleeve system for pipespreading in a borehole, comprising: an expansion sleeve having a topend and a bottom end; a grout injection pipe having a first end, asecond end, an inlet and at least one outlet, the grout injection pipebeing insertable through the open top end of the expansion sleeve suchthat the at least one outlet is positionable within the expansion sleeveand the inlet is positionable adjacent the top end of the expansionsleeve; a high-solids grout mixture; a pump for pumping the high-solidsgrout mixture through the grout injection pipe and into the expansionsleeve; and a closing mechanism for closing the expansion sleeve aroundthe grout injection pipe.
 2. The semi-permeable expanding sleeve systemfor pipe spreading in a borehole of claim 1 wherein the expansion sleeveis made of a loose weave fabric having gaps between fibers of 0.03-to0.08 inches.
 3. The semi-permeable expanding sleeve system for pipespreading in a borehole of claim 1 wherein the expansion sleeve is madeof a natural burlap fabric.
 4. The semi-permeable expanding sleevesystem for pipe spreading in a borehole of claim 1 wherein the expansionsleeve is the same length as the pipes to be spread.
 5. Thesemi-permeable expanding sleeve system for pipe spreading in a boreholeof claim 1 wherein the expansion sleeve has a diameter equal to thediameter of the borehole minus two times the outer diameter of thesmallest pipe within the borehole.
 6. The semi-permeable expandingsleeve system for pipe spreading in a borehole of claim 1 wherein thegrout injection pipe is made of plastic.
 7. The semi-permeable expandingsleeve system for pipe spreading in a borehole of claim 1 furthercomprising a grout pipe cap for sealing the bottom end of the groutinjection pipe.
 8. The semi-permeable expanding sleeve system for pipespreading in a borehole of claim 1 wherein the grout injection pipe hasa plurality of outlets along a length of the grout injection pipe. 9.The semi-permeable expanding sleeve system for pipe spreading in aborehole of claim 1 wherein the grout mixture is made using ratios ofwater, silica sand, and bentonite clay such that the mixture is at least50% solids and further is at least 25% sand, by volume.
 10. Thesemi-permeable expanding sleeve system for pipe spreading in a boreholeof claim 1 wherein the pump is a positive-displacement pump.
 11. Amethod of spreading pipes in a borehole, comprising the steps of:providing an expansion sleeve and a grout injection pipe, the expansionsleeve having a top end and a bottom end and the grout injection pipehaving a top end, a bottom end, an inlet and at least one outlet;inserting the grout injection pipe into the expansion sleeve through thetop end of the expansion sleeve such that the at least one outlet of thegrout injection pipe is positioned within the expansion sleeve and theinlet of the grout injection pipe protrudes from the top end of theexpansion sleeve; closing the bottom end of the expansion sleeve tocreate a semi-permeable enclosure; inserting the semi-permeableenclosure into a borehole with pipes to be spread such that thesemi-permeable enclosure is positioned in a central location of theborehole relative to the pipes to be spread; pumping a grout mixturethrough the inlet of the grout injection pipe such that it travelsthrough the outlet of the grout injection pipe into the expansion sleevecausing the expansion sleeve to fill with grout and forcing the pipesoutward towards a wall of the borehole as the expansion sleeve expands.12. The method of claim 11 further comprising the step of closing thetop end of the expansion sleeve around the grout injection pipe.
 13. Themethod of claim 11 wherein the expansion sleeve is closed around thegrout injection pipe with a clamp.
 14. The method of claim 11 whereinthe expansion sleeve is made of a loose weave fabric having gaps betweenfibers of 0.03-to 0.08 inches.
 15. The method of claim 11 wherein theexpansion sleeve is made of a natural burlap fabric.
 16. The method ofclaim 11 wherein the expansion sleeve is the same length as the pipes tobe spread.
 17. The method of claim 11 wherein the expansion sleeve has adiameter equal to the diameter of the borehole minus two times the outerdiameter of the smallest pipe within the borehole.
 18. The method ofclaim 11 wherein the grout injection pipe is a tremie line.
 19. Themethod of claim 11 wherein the grout injection pipe is made of plastic.20. The method of claim 11 wherein the grout injection pipe is sealedwith a grout pipe cap.
 21. The method of claim 11 wherein the groutinjection pipe has a plurality of outlets along a length of the groutinjection pipe.
 22. The method of claim 11 wherein the high-solids groutmixture contains at least 50% solids by volume and at least 25% sand byvolume.
 23. The method of claim 11 wherein the pump is apositive-displacement pump.
 24. The method of claim 11 furthercomprising the step of trimming the top end of the expansion sleeve toallow the inlet of the grout injection pipe to protrude from theexpansion sleeve.
 25. The method of claim 11 further comprising the stepof connecting the inlet of the grout injection pipe to a water supplysystem.